Abstract: East Asia has been hypothesized to be separated into distinct northern and southern regions by a climatic barrier, which is an east−west-oriented arid zone at approximately 40° N in eastern China. However, the impacts of climate change and local environmental selection on widespread species in this area are still poorly understood. In this study, we generated extensive genomic data for the crop pest Aelia fieberi (Hemiptera: Pentatomidae), which was sampled across its entire distribution in China, and we used these data in combination with niche analyses to investigate its phylogeographic pattern and examine the impact of climate change on its population structure and demographic history. We found that A. fieberi comprised two genetic lineages (southern and northern) that diverged during the middle Pleistocene, leading to a distinct "south−north" genetic pattern; this divergence was probably triggered by Pleistocene climate change in the arid belt. The two lineages of A. fieberi both experienced population expansion after the Last Interglacial (LIG) until the Last Glacial Maximum (LGM) and experienced secondary contact in the late Pleistocene. Local environmental adaptation may play an important role in maintaining and/or reinforcing the south−north divergence. Our study provides a detailed example of how climatic barriers and local environmental selection collaborate to facilitate adaptation to heterogeneous landscapes in East Asia from a phylogeographic perspective.

Key words: East Asia, Aelia fieberi, climate change, local environmental selection, phylogeography